- High-quality optical glasses, some of which are produced in the LEITZ glass research laboratory with rare earth elements (for instance high refractive index and low dispersion).
- LEITZ anti-reflection coating specially matched with the glasses used.
- Multi-coating only when technically justified.
- Leitz Absorban cement for uniform colour transmission.
- Neutral, faithful colour rendering.
- Almost 100 % light transmission throughout the entire spectrum, great freedom from stray light.
- Very high state of correction even at full aperture; in Leitz lenses maximum aperture is a fully effective standard aperture.
- Good contrast rendering and high colour correction even at full aperture - also an important condition for high viewfinder contrast for optimum focusing.
- Identical, convenient arrangement of the aperture setting rings in all lenses with automatic diaphragm.
- Identical rotation direction of the lens focusing mounts and aperture setting rings.
- Preset diaphragm running on ball bearings; functionally reliable from -25 to 60 °C.
- Fast closing time of the spring-back diaphragm of only 38 msec in spite of a long closing distance.
- Short time parallax between shutter release and film exposure;
- The very slight bounce of the spring-back diaphragm achieves reproducible aperture values owing to the long closing distance (tolerance only 1/8 light value);
- Guarantee of high accuracy and therefore precise exposure with the various aperture values.
- Lens hood standard equipment of all LEICA R lenses.
- Precision-made, robust, durable and easily operated LEICA-R rapid lens changing bayonet.
- Front and rear elements are deeply recessed in the lens mount and therefore effectively protected.
- No projecting control levers or elements can be damaged when the lenses are put upside down on a table etc.
- High accuracy of fit of the two parts of the helical focusing mount. Matching according to requirements: brass with brass, brass with aluminium, and aluminium with aluminium. Components are individually ground.
- The high accuracy of fit requires only a thin film of grease. LEICA lenses have no layers of thick grease which in time ooze away.
- The helical focusing mounts of the LEICA lenses move smoothly and positively even after prolonged use.
- All lens parts are corrosion-protected.
- Sturdy construction, blow- and impact resistant.
- Each lens element is individually mounted.
- During lens assembly the various elements are matched individually according to a mathematical model on the basis of the +/- tolerances arising during manufacture.
Result: High, uniform Leitz production quality.
Source: LEICA Catalogue (January 1979).